When it comes to aperture grille monitors, even when comparing monitors that are both based on Trinitron CRTs, Sony always comes out on top by a ways due to two things: more vibrant colors (likely due to their specs on coating), and tighter focus, esp. in the corners (although no AG monitor has perfectly clear corner focus). The same can be said when comparing a Trinitron vs. a Diamondtron CRT, which is the CRT type in Samsung, as well as Iiyama and a few others (like NEC/Mitsubishi).
My personal opinion from use/ownership is :
Sony
Iiyama
Samsung
All three are top rate, and depending on your vision, and the software you are using to compare/calibrate, you may find little to no difference amongst them.